diff --git a/gnu/local.mk b/gnu/local.mk
index df1e76979c..834a6e5cee 100644
--- a/gnu/local.mk
+++ b/gnu/local.mk
@@ -774,6 +774,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/tcl-mkindex-deterministic.patch		\
   %D%/packages/patches/tclxml-3.2-install.patch			\
   %D%/packages/patches/tcsh-fix-autotest.patch			\
+  %D%/packages/patches/teensy-loader-cli-help.patch		\
   %D%/packages/patches/texi2html-document-encoding.patch	\
   %D%/packages/patches/texi2html-i18n.patch			\
   %D%/packages/patches/tidy-CVE-2015-5522+5523.patch		\
diff --git a/gnu/packages/flashing-tools.scm b/gnu/packages/flashing-tools.scm
index 37a10726e3..0ab8bc57ee 100644
--- a/gnu/packages/flashing-tools.scm
+++ b/gnu/packages/flashing-tools.scm
@@ -160,3 +160,54 @@ With dfu-util you are able to download firmware to your device or upload
 firmware from it.")
     (home-page "http://dfu-util.sourceforge.net/")
     (license gpl2+)))
+
+(define-public teensy-loader-cli
+  ;; The repo does not tag versions nor does it use releases, but a commit
+  ;; message says "Importing 2.1", while the sourcce still says "2.0". So pin
+  ;; to a fixed commit.
+  (let ((commit "f289b7a2e5627464044249f0e5742830e052e360"))
+    (package
+      (name "teensy-loader-cli")
+      (version (string-append "2.1-1." (string-take commit 7)))
+      (source
+       (origin
+         (method url-fetch)
+         (uri (string-append "https://github.com/PaulStoffregen/"
+                             "teensy_loader_cli/archive/" commit ".tar.gz"))
+         (sha256 (base32 "17wqc2q4fa473cy7f5m2yiyb9nq0qw7xal2kzrxzaikgm9rabsw8"))
+         (file-name (string-append "teensy-loader-cli-" version ".tar.gz" ))
+         (modules '((guix build utils)))
+         (snippet
+          `(begin
+             ;; Remove example flash files and teensy rebooter flash binaries.
+             (for-each delete-file (find-files "." "\\.(elf|hex)$"))
+             ;; Fix the version
+             (substitute* "teensy_loader_cli.c"
+               (("Teensy Loader, Command Line, Version 2.0\\\\n")
+                (string-append "Teensy Loader, Command Line, " ,version "\\n")))
+             #t))
+       (patches (search-patches "teensy-loader-cli-help.patch"))))
+      (build-system gnu-build-system)
+      (arguments
+       '(#:tests? #f ;; Makefile has no test target
+         #:make-flags (list "CC=gcc" (string-append "PREFIX=" %output))
+         #:phases
+         (modify-phases %standard-phases
+           (delete 'configure)
+           (replace 'install
+             (lambda* (#:key outputs #:allow-other-keys)
+               (let* ((out (assoc-ref outputs "out"))
+                      (bin (string-append out "/bin")))
+                 (install-file "teensy_loader_cli" bin)
+                 #t))))))
+      (inputs
+       `(("libusb-compat" ,libusb-compat)))
+      (synopsis "Command line firmware uploader for Teensy development boards")
+      (description
+       "The Teensy loader program communicates with your Teensy board when the
+HalfKay bootloader is running, so you can upload new programs and run them.
+
+You need to add the udev rules to make the Teensy update available for
+non-root users.")
+      (home-page "https://www.pjrc.com/teensy/loader_cli.html")
+      (license gpl3))))
diff --git a/gnu/packages/patches/teensy-loader-cli-help.patch b/gnu/packages/patches/teensy-loader-cli-help.patch
new file mode 100644
index 0000000000..8b3fda128a
--- /dev/null
+++ b/gnu/packages/patches/teensy-loader-cli-help.patch
@@ -0,0 +1,33 @@
+Add support for '-h' (help).
+
+https://github.com/PaulStoffregen/teensy_loader_cli/pull/26
+
+---
+ teensy_loader_cli.c | 4 +++-
+ 1 file changed, 3 insertions(+), 1 deletion(-)
+
+diff --git a/teensy_loader_cli.c b/teensy_loader_cli.c
+index d4a6cc5..0a06209 100644
+--- a/teensy_loader_cli.c
++++ b/teensy_loader_cli.c
+@@ -37,7 +37,8 @@ void usage(const char *err)
+ {
+ 	if(err != NULL) fprintf(stderr, "%s\n\n", err);
+ 	fprintf(stderr,
+-		"Usage: teensy_loader_cli --mcu=<MCU> [-w] [-h] [-n] [-b] [-v] <file.hex>\n"
++		"Usage: teensy_loader_cli --mcu=<MCU> [-h] [-w] [-n] [-b] [-v] <file.hex>\n"
++		"\t-h : Print this help message\n"
+ 		"\t-w : Wait for device to appear\n"
+ 		"\t-r : Use hard reboot if device not online\n"
+ 		"\t-s : Use soft reboot if device not online (Teensy3.x only)\n"
+@@ -1081,6 +1082,7 @@ void parse_flag(char *arg)
+ 	int i;
+ 	for(i=1; arg[i]; i++) {
+ 		switch(arg[i]) {
++			case 'h': usage(NULL); break;
+ 			case 'w': wait_for_device_to_appear = 1; break;
+ 			case 'r': hard_reboot_device = 1; break;
+ 			case 's': soft_reboot_device = 1; break;
+-- 
+2.7.4
+